Unit 4: Chemical Nomenclature Section 1: Binary Compounds and Polyatomic Ions

Nomenclature Chemical naming system ▫ Two major types of naming groups  Ionic Compounds  Covalent Compounds

Ionic Compounds Bond that is formed between a cation and an anion (metal and a nonmetal). ▫ Three categories of Ionic compounds  Simple Binary compounds  Binary compounds with polyatomic ions  Binary compounds with stock system ions

Simple Binary Compounds Formed with only two parts ▫ A positive ion (cation) and a negative ion (anion)

Naming Binary Compounds Use the criss-cross method to make the formula. Write the name of the 1 st element – cation - (capitalized) Add the 1 st part of the name of the 2 nd element – anion - (not capitalized) End the 2 nd element with “ide” ▫ Example: NaCl Sodium and Chlorine Sodium chloride

Let’s Practice!

Binary Compounds with Polyatomic Ions Polyatomic Ion - A group of two or more elements that stay together and act as one ion ▫ Example: NH 4 +1  Nitrogen and 4 Hydrogen are combined into one ion with a total +1 charge

Common Polyatomic Ions NH 4 +  Ammonium NO 2 -  Nitrite NO 3 -  Nitrate SO 3 2-  Sulfite SO 4 2-  Sulfate OH -  Hydroxide PO 3 3-  Phosphite PO 4 3-  Phosphate CO 3 2-  Carbonate

Naming Binary Compounds with Polyatomic Ions Follow the same rules for how binary compounds are named However, use the EXACT name of the polyatomic ion (DO NOT CHANGE TO -ide!!!!!!) In many cases, you place parentheses around the polyatomic ion in the formula

Examples of Binary Compounds with Polyatomic Ions Sodium and Nitrate ▫ Formula: Na +1 and NO 3 -1  NaNO 3  Because there are 1 + and 1 -, nothing else is done; You do NOT need parentheses here because the charge is canceled ▫ Name: Sodium nitrate

Calcium and Phosphate ▫ Formula: Ca 2+ and PO 4 3-  Ca 3 (PO 4 ) 2  The parentheses shows that the entire phosphate ion gets doubled (VERY IMPORTANT) ▫ Name: Calcium phosphate Examples of Polyatomic Compounds

Let’s practice!!!